Yeah, i think that may of come from all of the abuse he took through the media and fans alike that he wasnt 'tough' enough.
I am always surprised people dont mention his fight against Mavrovic as well, that was a tough fight to grind out a win in what was a really grinding fight against a tough fighter
I have read a fair bit on Lewis and even Steward was always telling him to go for broke more often, which is what i think led to fights he could have easily won had he used his boxing brain more(exactly what he was criticised for in many fights)